df.h main.cpp df.h \( \begin{array}{l} 1 \text { \#ifndef DF_H } \\ 2 \text { \#define DF_H } \\ 3 \\ 4 \text { // Write your prototype here } \\ 5 \text { void cap(std::string \&s); } \\ 6 \\ 7 \text { \#endif } \\ \text { in.cpp } \\ 1 \text { \#include "df.h" } \\ 2 \text { \#include } \\ 3 \text { \#include } \\ 4 \text { using namespace std; } \\ 5 \\ 6 \text { int main() } \\ 7\{ \\ 8 \text { string s; } \\ 9 \text { cin >> s; } \\ 10 \text { // Print capitalized version of s } \\ 11 \quad \text { cout } \ll